Electronics continue to be incorporated into more products. Applications include industrial machinery to manufacture cars and package foods, as well as consumer products that detect keystrokes or the position of motors.
In order to properly control the mechanical components of a device it is critical to be able to measure the speed and position of the mechanical elements. The electronic components that perform such measurement are referred to as sensors.
For the applications described above, what is commonly used today is known as a Hall effect sensor. A Hall effect sensor has two primary components—a magnet and a p-type semiconductor. When the Hall effect sensor is activated a constant current is passed through the semiconductor. The current passes along a first axis. Separately, a voltage is measured across a second axis, perpendicular to the first axis.
As the magnet changes position relative to the semiconductor, the measured voltage across the second axis changes. The changes in voltage are used to calculate changes in the position of the magnet, which can be in turn used to calculate distance and speed.
The primary drawback of a Hall effect sensor is its need for constant power. Removing the current deactivates the sensor.
Given that many applications for position and speed sensors include applications using battery power, consumption is a concern. Eliminating the need for constant power results in superior battery life and an improved product.
What is needed is an alternative sensor that provides the versatility of a Hall effect sensor, but without the drawback of requiring constant power.